package com.MutiModule.simpleRPC;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 一个简单的RPC框架使用，暴露服务，引用服务
 * @author alexgaoyh
 *
 */
public class RpcFramework {

	/**
	 * 暴露服务
	 * 
	 * @param service
	 *            服务实现
	 * @param port
	 *            服务端口
	 * @throws Exception
	 */
	public static void export(final Object service, int port) throws Exception {
		if (service == null)
			throw new IllegalArgumentException("service instance == null");
		if (port <= 0 || port > 65535)
			throw new IllegalArgumentException("Invalid port " + port);
		System.out.println("Export service " + service.getClass().getName() + " on port " + port);
		ServerSocket server = new ServerSocket(port);
		for (;;) {
			try {
				final Socket socket = server.accept();
				new Thread(new Runnable() {
					@Override
					public void run() {
						try {
							try {
								ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
								try {
									String methodName = input.readUTF();
									Class<?>[] parameterTypes = (Class<?>[]) input.readObject();
									Object[] arguments = (Object[]) input.readObject();
									ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
									try {
										Method method = service.getClass().getMethod(methodName, parameterTypes);
										Object result = method.invoke(service, arguments);
										output.writeObject(result);
									} catch (Throwable t) {
										output.writeObject(t);
									} finally {
										output.close();
									}
								} finally {
									input.close();
								}
							} finally {
								socket.close();
							}
						} catch (Exception e) {
							e.printStackTrace();
						}
					}
				}).start();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * 引用服务
	 * 
	 * @param <T>
	 *            接口泛型
	 * @param interfaceClass
	 *            接口类型
	 * @param host
	 *            服务器主机名
	 * @param port
	 *            服务器端口
	 * @return 远程服务
	 * @throws Exception
	 */
	@SuppressWarnings("unchecked")
	public static <T> T refer(final Class<T> interfaceClass, final String host, final int port) throws Exception {
		if (interfaceClass == null)
			throw new IllegalArgumentException("Interface class == null");
		if (!interfaceClass.isInterface())
			throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class!");
		if (host == null || host.length() == 0)
			throw new IllegalArgumentException("Host == null!");
		if (port <= 0 || port > 65535)
			throw new IllegalArgumentException("Invalid port " + port);
		System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
		// 返回代理类的一个实例。返回后的代理类可以当作被代理类使用。
		/* 参数java.lang.ClassLoader：这是类加载器类，负责将类的字节码装载到 Java 虚拟机（JVM）中并为其定义类对象，然后该类才能被使用。
			 Proxy 静态方法生成动态代理类同样需要通过类加载器来进行加载才能使用，它与普通类的唯一区别就是其字节码是由 JVM 在运行时动态生成的而非预存在于任何一个 .class 文件中。
			 每次生成动态代理类对象时都需要指定一个类加载器对象。*/
		/* interfaces即代理类所要实现的接口，一般是被代理类所实现的全部接口的数组。*/
		return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[] { interfaceClass },
				new InvocationHandler() {
					public Object invoke(Object proxy, Method method, Object[] arguments) throws Throwable {
						Socket socket = new Socket(host, port);
						try {
							ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
							try {
								output.writeUTF(method.getName());
								output.writeObject(method.getParameterTypes());
								output.writeObject(arguments);
								ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
								try {
									Object result = input.readObject();
									if (result instanceof Throwable) {
										throw (Throwable) result;
									}
									return result;
								} finally {
									input.close();
								}
							} finally {
								output.close();
							}
						} finally {
							socket.close();
						}
					}
				});
	}
}
